Detect Default Accounts in Sumo Logic CSE
Adversaries may obtain and abuse credentials of a default account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Default accounts are those built into an OS (e.g., Guest or Administrator on Windows, root on Linux), preset on network devices/appliances, or created automatically by software integrations (e.g., vpxuser on ESXi when joined to vCenter). Adversaries exploit organizations that fail to disable, rename, or change the passwords of these accounts post-installation.
MITRE ATT&CK
- Technique
- T1078 Valid Accounts
- Sub-technique
- T1078.001 Default Accounts
- Canonical reference
- https://attack.mitre.org/techniques/T1078/001/
Sumo Detection Query
(_sourceCategory=*windows/security* OR _sourceCategory=*windows/sysmon*)
| where EventCode in ("4624","4625","4648","1")
| eval TargetUser = if(!isNull(TargetUserName), TargetUserName, if(!isNull(User), User, ""))
| eval TargetUser_lower = toLowerCase(TargetUser)
| where (TargetUser_lower in ("administrator","guest","defaultaccount","defaultuser","admin","root","vpxuser","dcadmin","sysadmin","service","support","user","test","demo","operator","sa","netadmin"))
OR (EventCode = "1" AND (
matches(toLowerCase(CommandLine), "net user (defaultaccount|guest|administrator) /active:yes")
OR matches(toLowerCase(CommandLine), "net localgroup administrators (guest|defaultaccount|administrator)")
))
| eval EventType = if(EventCode="4624","SuccessfulLogon",if(EventCode="4625","FailedLogon",if(EventCode="4648","ExplicitCredentialLogon",if(EventCode="1","ProcessCreation","Unknown"))))
| eval LogonTypeLabel = if(LogonType="2","Interactive",if(LogonType="3","Network",if(LogonType="7","Unlock",if(LogonType="10","RemoteInteractive",if(LogonType="4","Batch",if(LogonType="5","Service",LogonType))))))
| fields _messageTime, _sourceHost, EventCode, EventType, TargetUser_lower as TargetUser, LogonTypeLabel, IpAddress, WorkstationName, CommandLine
| sort by _messageTime descSumo Logic query detecting Windows Security logon events (EventCode 4624, 4625, 4648) where the resolved target account name matches the default built-in account list, and Sysmon process creation events (EventCode 1) with command lines that activate or add default accounts to privileged groups. Uses nested if() for event-type and logon-type labeling and the matches() function for regex-based command-line inspection against both Security and Sysmon source categories.
Data Sources
Required Tables
False Positives & Tuning
- Helpdesk and IT operations staff with documented break-glass procedures using the built-in Administrator account during outages or access recovery scenarios approved in ITSM.
- Security scanning tools (Nessus, Qualys, Rapid7) using default credentials for authenticated scanning of internal assets during authorized and scheduled assessment windows.
- Containerized or virtualized workloads using generic account names (admin, service, test) that are isolated, non-domain-joined, and explicitly permitted by application security policy.
Other platforms for T1078.001
Testing Methodology
Validate this detection against 4 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Enable and Use Built-in DefaultAccount via PowerShell (Magic Hound TTP)
Expected signal: Sysmon Event ID 1: Process Create with CommandLine containing 'net user DefaultAccount /active:yes'. Windows Security Event ID 4722 (User Account Enabled) with TargetUserName=DefaultAccount. Windows Security Event ID 4725 (User Account Disabled) after cleanup. Security Event ID 4688 (process creation) if command-line auditing is enabled.
- Test 2Enable Built-in Guest Account and Verify Access
Expected signal: Windows Security Event ID 4722 (User Account Enabled) with TargetUserName=Guest. Windows Security Event ID 4688 or Sysmon Event ID 1 with CommandLine 'net user Guest /active:yes'. Security Event ID 4625 if subsequent logon attempt is made. Event ID 4725 on cleanup.
- Test 3Authenticate Using Built-in Administrator Account via Net Use (HyperStack-style IPC$ Access)
Expected signal: Windows Security Event ID 4648 (Logon using explicit credentials) with TargetUserName=Administrator and TargetServerName=127.0.0.1. Windows Security Event ID 4624 (logon type 3 - Network) or 4625 (failed logon) on the target host. Sysmon Event ID 1 with CommandLine 'net use \\127.0.0.1\IPC$'. Sysmon Event ID 3 (network connection) to port 445.
- Test 4Simulate Default Service Account Logon via Scheduled Task
Expected signal: Windows Security Event ID 4698 (Scheduled Task Created) with task name 'DefaultAccountTest'. Windows Security Event ID 4624 (SYSTEM logon type 5) when task executes. Sysmon Event ID 1 for schtasks.exe and cmd.exe processes. Sysmon Event ID 11 (File Created) for the output file in TEMP. Security Event ID 4699 (Scheduled Task Deleted) on cleanup.
References (14)
- https://attack.mitre.org/techniques/T1078/001/
- https://docs.microsoft.com/en-us/windows/security/identity-protection/access-control/local-accounts
- https://docs.aws.amazon.com/IAM/latest/UserGuide/id_root-user.html
- https://cloud.google.com/blog/topics/threat-intelligence/vmware-esxi-zero-day-bypass/
- https://pentera.io/blog/information-disclosure-in-vmware-vcenter/
- https://www.microsoft.com/security/blog/2020/04/02/attack-matrix-kubernetes/
- https://github.com/rapid7/metasploit-framework/tree/master/modules/exploits/linux/ssh
- https://www.cisa.gov/news-events/cybersecurity-advisories/aa24-249a
- https://www.sygnia.co/blog/elephant-beetle-an-organized-financial-threat/
- https://thedfirreport.com/2021/11/15/exchange-exploit-leads-to-domain-wide-ransomware/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1078.001/T1078.001.md
- https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4624
- https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4625
- https://learn.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4722
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